Update elements.xsd

looks like elementNameType validator is very strict. I've got an exception in dev mode:
#0 (Magento\Framework\Config\Dom\ValidationException): Element 'block', attribute 'name': [facet 'pattern'] The value '4d072daa2b95b9d3fd3995d2faaf2993' is not accepted by the pattern '[a-zA-Z][a-zA-Z\d\-_\.]*'.
Line: 645